Most lighting columns comprise a lighting unit (hereinafter referred simply as a lamp unit) supported by a rigid hollow column through which cabling passes for connecting the lamp unit to a ground located power source, conventionally underground cabling from a mains source of electricity. With such lighting columns, when access is required to the top of the column to, for example, service, repair or replace a lamp unit, this is conventionally achieved either by employing a sky-lift or, where road access is limited to inhibit or prevent such use, by an operator climbing a ladder supported by the column. Recent legislation has recommended against the use of ladders to service lighting columns for a variety of reasons.
To address this and other problems, lighting columns have been developed in which the upper lamp unit supporting section of the column is pivotally secured to the lower ground supported column section through a hinge assembly. In such columns access at ground level to the upper column section and the lamp unit is achieved by causing the upper section of the column to pivot about the hinge assembly relative to the lower section.
An important criterion for any such column is to ensure that the presence of the hinge assembly which enables the upper column section to pivot relative to the column lower section does not present an area of structural weakness within the column during occasions when the column is subject, for example, to high wind loads which will vary depending on the geographical location of the installation. It is also important to ensure that when the upper column section is in its lowered position, it is secured against returning to its upright position until released to do so.
Applicant's patent GB2458393 discloses a column and hinge assembly which meet these criteria. This earlier patent discloses a hinge assembly which comprises an upper member pivotally attached to a lower member for movement about a generally horizontal axis. The upper part of the hinge assembly is secured to an upper section of a lighting column and the lower part of the hinge assembly is secured to a lower section of the column. In use, movement of the upper hinge part about the pivot axis from a normal position, in which the upper section of the column is relatively upright, causes the upper section of the column to rotate about the hinge axis thereby allowing the upper section of the column to be moved a generally horizontal maintenance position. The hinge assembly includes a cover rotatable about a generally vertical axis between a first position in which the cover impairs pivotal motion of the upper hinge assembly part and a second position in which such pivotal motion is permitted.
Whereas this hinge assembly works well in practise, the present invention sets out to provide an improved hinge assembly having enhanced resistance to wind loading together with an ability readily to increase the structural capacity of the cover sections to facilitate additional increased wind loading. Hinge assemblies in accordance with the invention have the advantage over known assemblies including that disclosed in GB2458393 or preventing unwanted pivoting of the upper hinge member and a column section connected thereto when the column section is in its generally horizontal position.